So everything that i read about safe pressures in a old actions refer to chamber pressure and with antique barrels made of basically mild steel  i can see how chamber pressure could be a consideration. however with a modern barrel of modern chrome molly steel it seem case head thrust to the bolt face would be more a factor than chamber psi. IE.. a 223 rem with ~ .300" case head area VS. a 308 win. with .385" of case head area at 62000 psi chamber pressure the .308 has nearly twice the case head thrust on the breech block of the .223. so is there a max case head thrust to the low wall breech face?

ssdave wrote on Oct 25^th, 2024 at 1:18pm:


thanks Dave, I have seen 38 special and also 357 mag and myriad others. which is what makes it so confusing.  then the miroku low wall being chambered in 63000 psi cartridges really throws off the curve. other than possible better steel 4140 chrome molly is only about 10.5% stronger than 1018 mild steel, why would the miroku low wall be two to three times stronger than the original high wall?

I bought my LW, chambered in 357 Mag, on a rebored 32cf barrel. I don't know how long or how many rounds were fired as a 357 Mag but, plenty from the looks of that area of the rifle.

Then, because that was long before this forum came to be, I rechambered it to 357 Max and fired it at least 500 times, with loads, with #9, that reached 1800+ fps, with a 208 gr GC bullet, 2100+ fps 146 gr GC bullet and a 208 gr PB, BSed bullet @ 1400 fps, with 4227.

So, I'm in the camp of Frank DeHaas @ 357 Mag as max thrust. That is the info I had on them, before I got my LW.

There are also rifles that at least one forum member use, that are chambered for 32/40, shot BSed.

That's just my experience but, they'll do better than 38 Spec.

rkba2nd wrote on Oct 26^th, 2024 at 2:58pm:

Or, could it be possible to fire it 50,000 more times and nothing detrimental happen?

Until someone does a actual stress analyzes, it's impossible to say what the thrust limit is. But, I will say this, if you start getting stretched cases, go no farther and magiflux it. If all is well, back off 2 gr or more.

Remember the low wall was designed for black powder pistol rounds. It may hold up just fine with 44-40 and 45 Colt, 13,000 and 16,000, but going higher may cause problems. The 38 Special came out as a smokeless cartridge but was designed to be reloaded with black or smokeless, same as the 32 Special. This applies to the original Winchesters, not modern rifles which may be designed for higher pressures.